COAL AND PETROLEUM
C
OAL AND PETROLEUM
Can air, water and soil be exhausted
by human activities? You have already
studied about water in Class VII. Is water
a limitless resource?
In the light of the availability of
various resources in nature, natural
resources can be broadly classified
into two kinds:
(i) Inexhaustible Natural Resources:
These resources are present in unlimited
quantity in nature and are not likely to
be exhausted by human activities.
Examples are: sunlight, air.
(ii) Exhaustible Natural Resources:
The
amount of these resources in nature is
limited. They can be exhausted by
human activities. Examples of these
resources are forests, wildlife, minerals,
coal, petroleum, natural gas etc.
Activity 3.2
(It is a group activity)
Take some containers. Fill them
with popcorn/peanuts/roasted
gram/toffees. Divide students into
groups of seven each. Further divide
each group into three subgroups
containing 1, 2 and 4 students.
Label them as first, second
and third generation respectively.
W
e use various materials for our
basic needs. Some of them are
found in nature and some
have been made by human efforts.
Activity 3.1
Make a list of various materials used
by us in daily life and classify them
as natural and man-made.
Natural Man-made
Can we use all our
natural resources
forever ?
Does this list include air, water, soil
and minerals? Since all these are
obtained from nature, they are called
natural resources.
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These sub-groups represent the
consumers. As population is
growing, second and third
generations have larger number of
consumers.
Put one full container for each
group on a table. Ask consumers of
the first generation from each group
to consume eatables from the
container of their group. Now, ask
the second generation consumers
from each group to do the same. Ask
students to observe carefully the
availability of eatables in each
container. If some thing is left in the
containers, ask third generation
from each group to consume it. Now,
finally observe whether all the
consumers of the third generation
got the eatables or not. Also observe
if anything is still left in any of the
containers.
Assume that the eatables in the
container represent the total
availability of an exhausible natural
resource like coal, petroleum or
natural gas. Each group may have a
different consumption pattern. Are
the earlier generations of any group
too greedy? It may be that the earlier
generations in some groups were
concerned about the coming
generation(s) and left something for
them.
In this chapter we will learn about
some exhaustible natural resources
like coal, petroleum and natural gas.
These were formed from the dead
remains of living organisms (fossils).
So, these are all known as fossil
fuels.
3.1 Coal
You may have seen coal or heard about
it (Fig. 3.1). It is as hard as stone and is
black in colour.
Fig. 3.1: Coal
Coal is one of the fuels used to cook
food. Earlier, it was used in railway
engines to produce steam to run the
engine. It is also used in thermal power
plants to produce electricity. Coal is also
used as a fuel in various industries.
Story of Coal
Where do we get
coal from and how
is it formed?
About 300 million years ago the
earth had dense forests in low lying
wetland areas. Due to natural processes,
like flooding, these forests got buried
under the soil. As more soil deposited
over them, they were compressed. The
temperature also rose as they sank
deeper and deeper. Under high pressure
and high temperature, dead plants got
slowly converted to coal. As coal
contains mainly carbon, the slow
process of conversion of dead vegetation
into coal is called carbonisation.
Since
it was formed from the remains of
vegetation, coal is also called a fossil fuel.
A coal mine is shown in Fig. 3.2.
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33
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Fig. 3.2: A coal mine
Coal Gas
Coal gas is obtained during the
processing of coal to get coke. It is used
Coal gas was used for street lighting
for the first time in London in 1810
and in New York around 1820. Now a
days, it is used as a source of heat
rather than light.
These days, bitumen, a petroleum
product, is used in place of coal-tar
for metalling the roads.
Fig. 3.3: Coal tar
When heated in air, coal burns and
produces mainly carbon dioxide gas.
Coal is processed in industry to get
some useful products such as coke, coal
tar and coal gas.
Coke
It is a tough, porous and black
substance. It is an almost pure form of
carbon. Coke is used in the manufacture
of steel and in the extraction of many
metals.
Coal Tar
It is a black, thick liquid (Fig. 3.3) with
an unpleasant smell. It is a mixture of
about 200 substances. Products
obtained from coal tar are used as
starting materials for manufacturing
various substances used in everyday
life and in industry, like synthetic
dyes, drugs, explosives, perfumes,
plastics, paints, photographic materials,
roofing materials, etc. Interestingly,
naphthalene balls used to repel moths
and other insects are also obtained from
coal tar.
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COAL AND PETROLEUM
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as a fuel in many industries situated
near the coal processing plants.
3.2 Petroleum
You know that petrol is used as a fuel in
light automobiles such as motor cycles/
scooters and cars. Heavy motor vehicles
like trucks and tractors run on diesel.
Petrol and diesel are obtained from a
natural resource called petroleum. The
word petroleum is derived from petra
(rock) and oleum (oil) as it is mined
from between the rocks under Earth as
shown in Fig. 3.4.
Do you know how petroleum is
formed?
Petroleum was formed from
organisms living in the sea. As these
organisms died, their bodies settled at
the bottom of the sea and got covered
with layers of sand and clay. Over
millions of years, absence of air, high
temperature and high pressure
Refining of Petroleum
Petroleum is a dark oily liquid. It has
an unpleasant odour. It is a mixture of
various constituents such as petroleum
gas, petrol, diesel, lubricating oil,
paraffin wax, etc. The process of
Fig. 3.4 : Petroleum and natural gas deposits
The world’s first oil well was drilled
in Pennsylvania, USA, in 1859. Eight
years later, in 1867, oil was struck
at Makum in Assam. In India, oil is
found in Assam, Gujarat, Mumbai
High and in the river basins of
Godavari and Krishna.
transformed the dead organisms into
petroleum and natural gas.
Look at Fig. 3.4. It shows the deposits
of petroleum and natural gas. You see
that the layer containing petroleum oil
and gas is above that of water. Why is it
so? Recall that oil and gas are lighter
than water and do not mix with it.
Wells
Gas
Oil
Water
Reservoir rock
Impervious
rock
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separating the various constituents/
fractions of petroleum is known as
refining. It is carried out in a petroleum
refinery (Fig. 3.5).
Various constituents of petroleum
and their uses are given in Table 3.1.
Many useful substances are obtained
from petroleum and natural gas.
These are termed as ‘Petrochemicals’.
These are used in the manufacture
of detergents, fibres (polyester, nylon,
acrylic etc.), polythene and other
man-made plastics. Hydrogen gas
obtained from natural gas, is used in
the production of fertilisers (urea).
Due to its great commercial
importance, petroleum is also called
‘black gold’.
3.3 Natural Gas
Natural gas is a very important fossil
fuel because it is easy to transport
through pipes. Natural gas is stored
under high pressure as compressed
natural gas (CNG). CNG is used for
power generation. It is now being used
Table 3.1 Various Constituents of Petroleum and their Uses
S.No. Constituents of Petroleum Uses
1. Petroleum Gas in Liquid form Fuel for home and industry
(LPG)
2. Petrol Motor fuel, aviation fuel, solvent for
dry cleaning
3. Kerosene Fuel for stoves, lamps and for jet aircrafts
4. Diesel Fuel for heavy motor vehicles, electric
generators
5. Lubricating oil Lubrication
6. Paraffin wax Ointments, candles, vaseline etc.
7. Bitumen Paints, road surfacing
Fig. 3.5: A petroleum refinery
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as a fuel for transport vehicles because
it is less polluting. It is a cleaner fuel.
The great advantage of CNG is that
it can be used directly for burning in
homes and factories where it can be
supplied through pipes. Such a network
of pipelines exists in Vadodara (Gujarat),
some parts of Delhi and other places.
Natural gas is also used as a starting
material for the manufacture of a number
of chemicals and fertilisers. India has vast
reserves of natural gas. In our country,
natural gas has been found in Tripura,
Rajasthan, Maharashtra and in the
Krishna Godavari delta.
3.4 Some Natural Resources
are Limited
You have studied in the beginning of
the chapter that some natural resources
are exhaustible like fossil fuels, forests,
minerals etc.
You know that coal and petroleum
are fossil fuels. It required the dead
organisms millions of years to get
converted into these fuels. On the
other hand, the known reserves of
these will last only a few hundred
years. Moreover, burning of these
fuels is a major cause of air pollution.
Their use is also linked to global
warming. It is therefore necessary that
we use these fuels only when
absolutely necessary. This will result
in better environment, smaller risk of
global warming and their availability
for a longer period of time.
In India, the Petroleum Conservation
Research Association (PCRA) advises
people how to save petrol/diesel while
driving. Their tips are
l drive at a constant and moderate
speed as far as possible,
l switch off the engine at traffic lights
or at a place where you have to wait,
l ensure correct tyre pressure.
l ensure regular maintenance of the
vehicle.
Can coal, petroleum
and natural gas be
prepared in the
laboratory from dead
organisms?
No. Their
formation is a very
slow process and
conditions for
their formation
cannot be created
in the laboratory.
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KEYWORDS KEYWORDS
KEYWORDS KEYWORDS
KEYWORDS
COAL
COAL GAS
COAL TAR
COKE
FOSSIL FUEL
NATURAL GAS
PETROLEUM
PETROLEUM
REFINERY
WHAT YOU HAVE LEARNT WHAT YOU HAVE LEARNT
WHAT YOU HAVE LEARNT WHAT YOU HAVE LEARNT
WHAT YOU HAVE LEARNT
Ü Coal, petroleum and natural gas are fossil
fuels.
Ü Fossil fuels were formed from the dead remains
of living organisms millions of years ago.
Ü Fossil fuels are exhaustible resources.
Ü Coke, coal tar and coal gas are the products
of coal.
Ü Petroleum gas, petrol, diesel, kerosene,
paraffin wax, lubricating oil are obtained by
refining petroleum.
Ü Coal and petroleum resources are limited. We
should use them judiciously.
Exercises
1. What are the advantages of using CNG and LPG as fuels?
2. Name the petroleum product used for surfacing of roads.
3. Describe how coal is formed from dead vegetation. What is this process
called?
4. Fill in the blanks.
(a) Fossil fuels are , and .
(b) Process of separation of different constituents from petroleum is
called .
(c) Least polluting fuel for vehicle is .
5. Tick True/False against the following statements.
(a) Fossil fuels can be made in the laboratory. (T/F)
(b) CNG is more polluting fuel than petrol. (T/F)
(c) Coke is almost pure form of carbon. (T/F)
(d) Coal tar is a mixture of various substances. (T/F)
(e) Kerosene is not a fossil fuel. (T/F)
6. Explain why fossil fuels are exhaustible natural resources.
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COAL AND PETROLEUM
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7. Describe characteristics and uses of coke.
8. Explain the process of formation of petroleum.
9. The following Table shows the total power shortage in India from
1991–1997. Show the data in the form of a graph. Plot shortage percentage
for the years on the Y-axis and the year on the X-axis.
S. No. Year Shortage (%)
1 1991 7.9
2 1992 7.8
3 1993 8.3
4 1994 7.4
5 1995 7.1
6 1996 9.2
7 1997 11.5
E X E R C I S E S
Extended Learning — Activities and Projects
1. Get an outline map of India. Mark the places in the map where
coal, petroleum and natural gas are found. Show the places where
petroleum refineries are situated.
2. Choose any five families of your neighbourhood. Enquire whether
their energy consumption (coal, gas, electricity, petrol, kerosene)
has increased or decreased in the last five years. Enquire also about
the measures they adopt to conserve energy.
3. Find out the location of major thermal power plants in India. What
could be the reasons for their being located at those places?
For more information, visit:
l www.energyarchive.ca.gov
l web.ccsd.k12.wy.us
l web.pcra.org
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